Embodiments of the invention relate generally to compressed air energy storage (CAES) systems and, more particularly, to secondary energy production via a CAES system.
CAES systems typically include a compression train having a plurality of compressors that compress intake air and provide the compressed air to a cavern or other compressed air storage volume. The compressed air is then later used to drive turbines to produce energy such as electrical energy. Often, if utility energy is used to power the compression train, the compression train operates during off-peak hours of utility plants while the energy production or generation stage of the CAES system typically operates during high energy demand times. However, this need not be the case in every instance. For example, energy generated from wind mills may be used to power the compression train while compressed air is delivered to the energy storage cavern or the like. In any event, the economics of the CAES system energy consumption versus CAES system energy production is typically a driving factor determining when the compression stage and the production stage operate.
During operation of the compression stage of a CAES system, the compressed air is typically cooled to cavern temperature, or at least close to cavern temperature, prior to storage. Generally, during the energy production stage of a CAES system, compressed air stored in the cavern is removed and heated. After heating, the compressed air is allowed to expand through one or more turbines, thus causing the turbine(s) to drive one or more generators to produce electricity. Effectively, the volume and pressure changes of the compressed air are utilized to produce electricity. Typically, however, other forms of energy transferred with the compressed air are not tapped to produce electricity therefrom. As such, CAES energy production may not be maximized.
Accordingly, it would be beneficial to have a method and system of maximizing energy production of a CAES system.